The International Day of Families is observed on the 15th of May every year. The Day was proclaimed by the UN General Assembly in 1993 with resolution A/RES/47/237 and reflects the importance the international community attaches to families. The International Day provides an opportunity to promote awareness of issues relating to families and to increase knowledge of the social, economic and demographic processes affecting families.

International Nurses Day (IND) is an international day celebrated around the world on 12 May (the anniversary of Florence Nightingale's birth) of each year, to mark the contributions nurses make to society.

World Thyroid Day celebrated on May 25.

The United Nations General Assembly declared May 3 to be World Press Freedom Day or just World Press Day to raise awareness of the importance of freedom of the press and remind governments of their duty to respect and uphold the right to freedom of expression enshrined under Article 19 of the 1948 Universal Declaration of Human Rights and marking the anniversary of the Windhoek Declaration, a statement of free press principles put together by African newspaper journalists in Windhoek in 1991.

The purpose of World Turtle Day, May 23, sponsored yearly since 2000 by American Tortoise Rescue, is to bring attention to, and increase knowledge of and respect for, turtles and tortoises, and encourage human action to help them survive and thrive.

World Turtle Day is celebrated around the globe in a variety of ways, from dressing up as turtles or wearing green summer dresses, to saving turtles caught on highways, to research activities. Turtle Day lesson plans and craft projects encourage teaching about turtles in classrooms.

28th May celebrated as International Day of Action for Women’s Health.

1st Tuesday of May celebrated as World Asthma Day.

National Technology Day of India celebrated on May 11.

International Museum Day (IMD) is an international day a celebration that held every year on or around 18 May, coordinated by the International Council of Museums (ICOM). The event highlights a specific theme that changes every year and that is at the heart of the international museum community’s preoccupations.

World Chronic Fatigue Syndrome Awareness Day celebrated on May 12.